Design of hydroponic wastewater recovery process for CO2, NOx, and NH3 utilization from crop residue burning gas.

Hydroponic wastewater recovery provides a green alternative to chemical fertilizers by recycling nutrients, yet transitioning to closed systems introduces problems such as pathogen proliferation and high sterilization costs. These challenges, along with the need for regular water analysis to correct nutrient imbalances, can hinder crop growth and increase expenses. However, hydroponic wastewater is also beneficial for capturing harmful emissions like CO2, NOx, and NH3, thanks to its rich mineral content. As it reacts with air pollutants, it produces compounds like Ca(NO3)2 and NH4NO3, turning pollutants into useful fertilizers. This study designed a novel hydroponic wastewater recovery process for CO2, NOx, and NH3 utilization from crop residue burning gas. through the following procedures: (1) ion separation of hydroponic wastewater, (2) NOx capture and utilization using precipitated Ca(OH)2, (3) NH3 capture and utilization using separated NO3− and SO42−, and (4) CO2 capture and utilization using KOH, Ca(OH)2 and Mg(OH)2. A process model was developed, and the economic feasibility of the proposed system was determined by calculating the total annualized cost. The result shows that approximately 85% of NOx, 99% of CO2, and 99% of NH3 were captured and utilized. Importantly, the total annualized cost of the system could decrease by 70% compared with that of the base process. [ABSTRACT FROM AUTHOR]